Respuesta :

Answer:

  $0.12

Step-by-step explanation:

0.4 kW for 3 hours is (0.4 kW)(3 H) = 1.2 kWh.

At $0.10 per kWh, the cost is ...

  (1.2 kWh)×($0.10/kWh) = $0.12

It costs 12 cents to run the amplifier for 3 hours.